Ultra Flash repair - "How To" thread - step by step tutorial
 

Hello guys,

After finishing off the Ultra Flash repair project i thought i'd share it with you for fun.
This Ultra Flash was owned and flown by a friend, and was crashed when he landed dead stick and hit an object with the left wing close to the root.
this caused a huge portion of the from of the wing root to be broken off, the fuselage be split into 2 along its left side, and many more side damages - broken/loose fuse ribs, many cracks in the fiberglass fuse, crashed wingtip etc.

I bought the crashed model from ym friend, and with the help of other friends, who work in UAV composite construction, the repair was made.

i will detail the repair in 4 major sections: fuselage, wing, fuel tank and elevator.

Lets go....

First 2 pics:
1. Yours truly flying this exact same model a few months before the original owner crashed it.
2. the damage to the wing leading edge root after the crash.

At this point we examined the spar inside and were happy to see it seems 100% un hurt - lucky!

At this point the model was given to Dudu Ifrah for repair. He and His Son Omri are both UAV composite builders here in Israel and with the help of Sharon Azulay (also UAV composite builder), they commensed work on the fuselage.

first stage was to expose the fiberglass around the main crack in the fuse - the fuse was split open!
Then it was first glue time. - Fuselage was held against the wing and the crack was held in place with aluminum tape from the outside (there was about 1mm gap in the crack), and structural glue was wicked into the slot, followed by 3 layers of stepped carbon fiber cloth, and then peel ply.
After this was dry another layer of glass was laid on the outer part of the crack with peel ply, dried and sanded smooth.
final touch was "stone" spray inside the fuse to give back the original interior look.

Next all the other cracks in the fuse were exposed, glass layed on both sides of them, peel ply, dry and sand smooth.

the intakes suffered some serious damage which was also repaired interior and exterior - view pics.

All cracks were primered grey and smoothened out, but after understanding that for proper color match we need white primer, then white primer was done.

This concludes the fuselage repair.

Next was the side fuel tank. it was torn out of the fuse after the crash, thus an entire side of it was broken off and missing.
Dudu profesionally cleaned ut, layed up several layers of fiberglass, and leak proofed it. works perfect!

both tanks were cleaned again and installed back into the fuselage.

Elevator was not broken, but was very scratched from being dragged through rubble.
it was sanded, spackled, primered grey, and eventually white.

Next was the main issue, and this is the wing.
The wing suffered a great deal of damage, albaeit luckily not structural.

1. huge chenk broke off the LH side root lading edge, almost all the way to the main spar!
2. smashed (soft to touch) wing tip).

this was thought for some time and we decided to go the old fashion way - carved foam blocks, glue them to the wing and laminate them.

first step was to clean off the broken area, cut some foam blocks to match wing contour (as close as possible) using hot wire, and glue the foam to the wings.
Then glue a pine wood lading edge spar.

Next step was to laminate the entire assmbly of foam / leading edge with thickedned epoxy (this is actually a small amount!) and laminate with thin CF sheet, to create the lower laminate layer.
this laminate was later sealed at the leading edge with another carbon fiber strip lapped over the LE.

This was left to dרy, sanded and then another coat of epoxy with the external CF laminate overlapping outside of the broken piece, into the wing to a joggle (original glass removed around the broken part, and airex was exposed creating a joggle).
after all of this glass cloth for finish.

Finish to the wing reconstruction concluded of spackle, primer, sanding and vice versae.

wing tip was drilled with holes, and thin CA wicked into the collapsed Airex core with a syringe.
then exposed the whole external area and glassed with peel ply.
later sanded smooth and finished with spackle and primer.

Then the model was ready for Aviram Katz, another UAV composite builder, who in turn was the painter.

all original paints ordered from CARF for that perfect repair ;)

Note: Every point you see primered had a crack which was exposed, glassed, and finished.
as you can see, almost all parts of the model were damaged!

I dont have many pictures of the painting process, but painting in Aviram's talented hands required a lof of masking and a lot of patience as he painted each color on a different day to allow full curing between color coats.
for example every color on the fuse (white, black, anzherit, orange) required masking off the entire fuselage leaving open only the pars that required that specific paint.

it was decided to reconstruct original scheme (as i like it very much) despite the fact that most parts on the model actually suffered damage and required re painting!
more parts were repainted than parts that werent.

pictures of the painting process are pretty much self explainatory so i will leave them as they are.

END RESULT -
here she is in all of her glory !! after a lof of hard work from good friends:
Dudu Ifrah
Omri Ifrah
Sharon Azulay
Aviram Katz


Thank you guys !!

Before and After:

Wow! that really came back from the dead Lior - very impressive work by the whole team!!

nice work great job

Awesome work. An inspiration to us all!

well done. It will probably fly awesome as well.

Respect!

Tanks all..yes that was a special work...a lot of thinking how can we repair the crush. bat after the planning stage we started to work and you can see the resulte.
so again thaks you all for you compliments...
Omri

Impressive.

Nicely done i3dm, thanks for sharing ..
dbsonic is absolutely right.. It will fly much better after this repair.. ;) (For some reason, all my models fly better after they have been beaten up a little bit..)

Yes they do.. the pilot has a free plane, so he flies it with aggression.. :)

My classic needed work after I bought it and probably something like 300 flights later, it's still going strong. I say a Flash is worth fixing.

You guys are all right. :)